1. Field of the Invention
The present invention relates to a method of manufacturing a semiconductor device through a substrate processing process, and relates to a cleaning method and a substrate processing apparatus.
2. Description of the Related Art
As a method of forming a predetermined film on a substrate, there is a chemical vapor deposition (CVD) method. In a CVD method, two or more sources are caused to react with each other in a gaseous state or on the surface of a substrate to form a film including elements of source molecules on the substrate. As another method of forming a predetermined film on a substrate, there is an atomic layer deposition (ALD) method. In an ALD method, two or more film-forming sources are alternately supplied to a substrate under predetermined film formation conditions (temperature, time, etc.), and the sources are adsorbed on the substrate on an atomic layer basis to form a film by a surface reaction. As compared with a conventional CVD method, the ALD process can be performed at a lower substrate temperature (process temperature), and the thickness of a film formed on a substrate can be controlled by adjusting the execution number of a film-forming cycle.
An aluminum nitride (AlN) film and a titanium nitride (TiN) film are examples of a conductive film that can be formed on a substrate. In addition, there are examples of other conductive films such as a tantalum (Ta) film, a tungsten (W) film, a manganese (Mn) film, a film made of a nitride thereof, a titanium (Ti) film, and an aluminum (Al) film. In addition, examples of insulating films include a film formed by oxidizing Hf, Zr, or Al, and a film formed by nitriding Hf, Zr, or Al.
Such a conductive film or insulating film may be formed by supplying a process gas into a processing chamber in which a substrate is loaded. However, when such a conductive film or insulating film is formed, deposited materials including such a conductive film or insulating film are adhered to the inner wall of the processing chamber and a substrate supporting tool disposed in the processing chamber. If a film is deposited on the inside of the processing chamber to a large thickness, the film may crack due to increasing stresses, and thus contaminants (such as adhered materials that were stripped from the inside of the processing chamber) may be generated. If such contaminants permeate the conductive film or insulating film formed on the substrate, the product process yield may be decreased. Therefore, each time the thickness of a film formed by deposited materials reaches a predetermined value, it is necessary to remove the film. For this, it is preferable that deposited materials are removed by etching them using a cleaning gas without disassembling the processing chamber. If a film can be removed by a cleaning gas, since it is not necessary to disassemble the processing chamber, manpower can be saved, and breakage of processing chamber components can be prevented. Therefore, operational costs can be reduced, and the operating rate of an apparatus can be improved. For example, Patent Document 1 below discloses etching technology of a film such as an insulating film by using BCl3.
[Patent Document 1] Japanese Unexamined Patent Application Publication No. 2004-146787
When an aluminum nitride film is formed on a substrate as a conductive film, for example, trimethylaluminum (TMA, Al(CH3)3) may be used as an aluminum (Al)-containing source, and ammonia (NH3) may be used a nitriding gas. An aluminum nitride film is used as an insulating film, and by stacked an aluminum nitride film on a titanium (TiN) film in an alternating manner, the aluminum nitride film can be used for forming an electrode.
However, if an aluminum nitride film is etched by using BCl3 (halogen-base gas) as a cleaning gas, the aluminum nitride film is not sufficiently etched so that it is difficult to remove the aluminum nitride film completely.